Georgetown seems to have, shall we say, a flexible approach to deadlines. First there were all those extensions to the application deadline. Now this with the waitlist. And they said that there would be message boards available on the admitted students website starting yesterday, but they're still not there.
They also told admitted students who sent in the first tuition deposit that they would get a second mailing through US mail in "early May". Then they decided not to mail anything at all, but sent a mass e-mail on May 12. That's mid-May, if you ask me.